Vehicle signaling



3 Sheets-Sheet l wm. h.

...RWE

INVENTORl Dec. l, 1953 T. M. FERRILL, JR

VEHICLE SIGNALING Filed July 19, 1946 NN MN! Dec. 1, '1953 T. M. FERRILL., .1Rl 2,661,070

VEHICLE SIGNALING Filed July 19, 1946 3 sheets-sheet 2 INVENTOR Dc. l, 1953 T. M. FERRILL, JR 2,661,070

VEHICLE SIGNALING FiledjJuly 19, 194e 5 sheets-sheet 5 FREQUENCY INVENTOR Patented Dec. 1, 1953 STATES meterte SIQMNQ @me M- Jff @we et l 11 @eine te@ space (or iene-7 1).

Figs. 5 and 6 are schematic views of railway vehicles equipped for rs g recording and relying upon speed control sigfi's that the performance media I5, I'I are illustrated 'in Fig. l as extending eem-@ee the feite 492,421, @et *mail be ...Roisitond 'in any convenient @nner @long the l*raglg way, as alongside 'or' abol'tie ''a'sL "'Trofley units extend from the ehicle I I for riding along the recording media.. Upon these trolley units are .Qar-.riedgmagnetic recorder heads ,23;z5orsehjtheireteminemie to intense mag;

natie ms durinepr @i tire irehisle :LLI

tiene .1.159932 Elsiexfreeolgdine .Qoresnendme Meer-reti@ ne and tapes, the recording medium being driven at constant speed through a recorder head during the subjection of the recorder head to intense alternating signal currents, and being driven at an equal constant speed through a pickup head for faithful tonal reproduction. Representative instruments and techniques employed for this purpose are set forth in a paper by S. J. Begun entitled Magnetic Recording and Some of Its Applications in the Broadcast Field, Proceedings of the I. R. E., vol. 29, page 423, August 1941. The elements described in the Begun paper, including recorder and pickup heads and recording media, are applicable to the present invention, the recording medium here being fixed along the vehicle path, and the relative motion between the recording medium and the recorder and pickup heads being provided by the vehicle movement along the path, the speed of this relative motion varying according to the vehicle speed.

Fig. 2 illustrates in vertical cross-section an arrangement of at strips I5 and I1 as the recording media, supported by standards I2 and I4 stationed upon the cross-ties. Such strips are ideally suited for transverse polar recording.

Fig. 3 illustrates an arrangement between the rails I9 and 2I of ferrous wires I3 and I8 as the recording media, supported as by cross-brackets 20 upon standards 22. If small-diameter wires I6 and I8 are employed as the recording media, either transverse recording or longitudinal recording may be employed. Each of these methods is illustrated in the Begun paper, supra.

Referring again to Fig. 1, an oscillator or alternating signal generator 21 may be coupled to a trolley-borne recorder head 23, as through an amplifier 29, for producing a speed reference recording along the medium I5. The number :c of cycles per foot along the medium I5 is made to vary according to the quotient of the frequency f of oscillator 21, expressed in cycles per second, and the speed v of the vehicle II, expressed in feet per second, the equation relating these factors being simply:

A vehicle 3l (Fig. 4) is thereafter operated along the railway I3, with pickup heads 33 and 35 trolley-borne therefrom for cooperation with the recording media I and I1, respectively. Pickup head 33 produces an alternating signal voltage of frequency f varying as the product of the speed v of vehicle 3l multiplied by the number of cycles per foot along the medium I5. Thus, the frequency f of the signal generated in pickup head 33 by the movement of the vehicle 3I is given by the equation:

l=xvl From a consideration of the two foregoing equationsI it is apparent that fl vl f v and, accordingly, that any variance between the speeds of the subsequent vehicle 3I and the recording vehicle II is represented by variations of the picked-up frequency j above or below the recorded frequency f. Following the general principles set out in patent application Serial No. 523,737, the signal produced by pickup head 33 may be amplified and utilized through suitable servo mechanism 36 for controlling Vthe speed 4 control members, e. g., the throttle 31 and the brake control device 39 of the vehicle 3|.

The servo mechanism 36 includes an amplifier 4I having its input terminals connected to the pickup head 33 and its output terminals connected to low-pass and high-pass filters 43 and 45. The output circuits of these filters are connected to the input circuit of a servo amplier 41 through rectifiers 49 and 58, and the output circuit of the servo amplifier 41 controls a motor 53 according to the magnitude and rate of change of the difference of the rectified output voltages of the filters 43 and 45. The servo motor 53 is coupled, as through gear elements `55, 51 and 59 to the throttle 31, and a projection 'BI on the gear element 59 may be arranged to actuate the brake control lever 39 as the closed-throttle position is reached by the gear element 59.

The high-pass and low-pass filters 43 and 45 are arranged to provide equal attenuations at the average frequency f recorded through recorder head 23 during the traversal of the railway I3 by the recorder vehicle II. Assume for the moment that the oscillator 21 remained adjusted to a fixed frequency during the traversal of railway I3 by vehicle II. Insofar as the speed of the vehicle'3l varied along successive portions of the railway I3 in exact duplication of the prior performance therealong of the recorder vehicle II, the signals rectified in rectiers 43 and 58 and opposed in the servo amplifier 41 would be of equal strength, and the motor 53 would therefore remain inactive. But if the speed of the vehicle 3| should become excessive, the frequency of the signal developed in the pickup head 33 would be proportionately higher than the recorder frequency, and thus the signal passed through the high-pass filter 43 and rectifier 49 would be stronger than that passed through units 45 and 58, the differential signal supplied to the servo amplifier 41 being effective to operate the servo motor 53 in the direction to decelerate the vehicle 3|. The speed displacement signal differential between the rectied filter output voltages would be modified in servo amplifier 41 according to its rate of change, with reinforcement of the operating voltage supplied to motor 53 when the differential input signal of servo amplifier 41 is increasing, and suppression of the motor operating Voltage when the servo amplifier differential input signal is decreasing, as set forth in application Serial No. 523,737.

While the above discussion assumed fixed-frequency operation of oscillator 21, it will be readily apparent that the frequency of the oscillator may be varied somewhat above and below a predetermined average frequency, as for denoting throttle adjustment, as will appear more fully hereafter.

Auxiliary signals may be recorded along signicant parts of the railway I3, e. g., at the approaches to stations or to hazardous zones, as by significant tones or by voice signals which may be employed through a microphone 65 and amplier l(i1 (Fig. l) for actuation of the recorder head 25 cooperating with recording medium I1. Pickup head 35 on vehicle 3I (Fig. 4)

- is coupled through an amplifier 59 to a transaecomo proyisitui is useful, turn, vas ani .admet :to the speed. dupiication Even musical tones are recorded through. 'elements 65?, 61, 2.5, and arereproduced through pickup :head 3a and transducer It, an indication or any error in the' speedduplication performance is available tliifoiigl'iobservance of :resultant lack of vfidelity or' naturaliiess of the tones coming through transducer" It.

In 5 Iand e tnereare shown similar vehielos I5 and. "n :arrangedrfor operation along a patri-arene which entends a recording medium 1. Vehicles #sand 111 preferably aregenerally similar, :andy preferably have substantially `duplisate throttleeq-uipment and. substantially vduplicate characteristics :as tovariation of .motive povver'tfith throttle position. In each of these Vehicles, -aiiampi-incr 6| `lzirovided with `an output amplitude limiter Vcmineoted :to supply signal energy to a frefmeneyk discriminator '83, and the output circuit of the lfrequency 'discriiiiinator lis connected kto aetuate a servo Yino-tor 85'. The servo motor-Sile coupledthrough speed reduction gears 81, 89 anda further connecting element,- e. g. a belt or cord loop isi passing through a return pulley 93 "to the throttle-lever 95. Iffdesiredf the servo motor 85 Amay be coupled also to the 'vehicle brake lever 9i, as by a furtherV belt oi cord, portions of the belts or cords being' elastic if desired. A potentiometer 99' energized"byuJ voltage'e-y source -I lli is connected in the circuit betweenr the `frequency discriminato'r 83=and themotoi, `and this potentiometer 99 is coupled to 'the -inotor 05, as through the throttle coupling members, ffor providing' an outpuit voltage varying as a `predetermined funeti'on Aof the setting of the -throttle lever 95. A hired voltage source |03'may be connected to the `motor 85 for supplying 4power to the armature thereof, and for inducing Yrotation of the motor rotor a direction and ata speeddependent upon the polarityandmagnitude ofthe resultant Y voltage applied to the motor field winding termihals-105,- -ii e., lthe 4diierence -between the voltages 'provided by potentiometercircuit "99, 10| and the frequency discriminator v83.

The connections between the frequency discriminator 183 and the servo motorf' arefso arranged 'that -a reduction of frequency vof the signal supplied through amplier lil `vto the vinput terminals fof the discriminator '33 causes change inthe output voltage of-'the discriminator whichactuatesthe motor 'B5 in Vthe-direction to advance the throttle 95, `and thus to increase the vehicle motive power. VConversely, an incraseoi'irequency results in movement of the throttle toward the closed position. The-extent by which the throttle is advanced orVV retracted by a changeof discriminator input frequency-and the resulting change of discriminator output voltage is limited to a substantially proportionate changeiof throttle setting, because the movement of the-throttle is accompanied .by a change of the Aoutput voltage of the potentiometer circuit 99,101 as required to oppose fully `rthe'change of the discriminator output voltage.

Vehicle 15, which .may be 'the leading car or control-car of an urban rapid-transittrain, for example, is provided with-a variable-frequency signal source-such as a ,tunable oscillator l0?, connected to supplya generated tone signal to the input terminals othefarnpliiier 8l. 2A lever |09 may beattached `to the frequency control dial -Iil fo'f theosoillator |91 and-the lever may Y' position at whiclroscillatorf |101' produces annui.- put signal. frequency corresponding to. a nearly closed. .throttle condition. 'With this: arrangement, the intel-'coupled units 8i, 33, 85, k89 and 98 copei-ate as. a servo system for varying the setting of the throttle ina predetermined relation :to the frequency of theoscillator |01, yand similarly, in predetermined: relation. to the deiiection oi the lever |09.

A recorder head 'Ii'i carried upona trolley arm iliiand. adapted to cooperate with the recording medium 19 is connected to the output .terminals of'tlieamplier di.

An experienced, capable operator, thoroughly familiar with all peculiarities of the routeover which the recording'medium 1i? extends, is ernployed to operate-the vvehicle 15 along the route at `the' optimum speeds, so that a master recording may be'impressed `upon the medium 19 through the recorder head H1. The operator does not directly manipulate the usual 'control elements Sii and 975, ybut instead, he controls the vehicle performance through manipulation of the lever [0s on oscillator ici. The vehicle motive power is increased by advancing the lever |99 and thus reducing the frequency of the oscillator |01, or it is decreased by retracting the lever toincrease the oscillator frequency. The signal frequency applied tothe recorder head H1 thus does not remain constant; instead, it varies viniinediately withmanipulations ofthe master control lever |09, and hence with variationsof setting of thethrottle 91.

vAfter the traversal of the medium 19 'by the recorder head 1 under theiniiuence of the amplied output of the oscillator |01, the recording medium 19 remains conditioned for automatically enabling vehicles to duplicate theperformance of the first vehicle 15. Vehicle 11 (Fig. 6) is made to-repeat exactly the'speed variations of thepreceding vehicle 15'by energization of the input'circuit-of its amplifier 8| through a pickup head |2I carried on a trolley arm |23. `Since the amplifier 83 in each of the'vehicles 15 and 11 is arranged for producing an output vvoltage substantially independent of the-input signal'amp'litude, the throttle settings of the vehicles are varied substantially equally in responseto equal frequency deviations of the amplified signals. Therefore, las the second vehicle 11 traverses'the medium 19, the output voltage developed bythe frequency discriminator Vcarried thereby varies substantially identically with the previous variations of output of the frequency discriminator carried'by the recorder vehicle 15. As a result, the throttle of vehicle 11 is made-to accurately follow the settings of the throttleof vehicle 15, and so vehicle 11 duplicates the speed performance of vehicle 1,5 in every'respect,

An amplier circuit arrangement suitable for the amplifiers l8| in Figs. 5 and 6, and for the amplifiers `29 and 4| in Figs. l and 4, isset forth in Fig. 7. VTwo conventional resistance-capacitance coupled voltage amplier'stages |25 and |21 are follovved'by a power output-,stage |29, transformer coupled to the amplifier output terminals. Remote cut-oli screen-grid or pentode'tubes preferably are used in the voltage amplifier Vstages |25 and |21. An automatic gain control Yvoltage generator stage v|-3`I is provided in the ampliiier, with a triode |33 having `a grid circuit biased beyond the anode current cut-off point by'a bias voltage source |35.' A voltage source |31 is emplayed for maintaining the cathodeof ltriode "|33 at a predetermined negative potential :below ground. The grid of tube |33 is coupled through a capacitor |39 and resistor |4| to the anode output terminal of the power output stage |29. An automatic gain control voltage drop resistor |43 and storage capacitor |45 in shunt therewith are connected between the anode of stage |3| and ground, and the anode of the gain control stage |3| is connected through grid resistors |41 and |49 to the control grids of stages |25 and |21, for increasing the negative bias voltage and thus decreasing the gain of these stages as the output voltage of the stage |29 increases.

Production of an output voltage of the desired level in the anode circuit of stage |28 results in current pulses through tube |33 of such magnitude as to maintain a normal bias voltage level across capacitor |45. A very small change of amplifier output voltage results in a relatively great change of voltage across capacitor |45, and hence a great change of gain of each of stages |25 and |21. Therefore, the output voltage level of the amplier is held substantially constant with wide changes of input signal level.

The circuit details of a frequency discriminator 83 are set forth in Fig. 8. A first amplifier stage is coupled to the discriminator input terminals by a low-pass filter which may consist simply of a series resistor |53 and a shunt capacitor |55 connected to the control grid of stage |5|. pled to the input terminals by a high-pass filter which may also be a resistance-capacitance circuit, as with a series capacitor |59 and a shunt resistor |6|. Each of the two amplifier stages |5| and |51 is provided with a transformercoupled full-wave rectfying circuit and resistance-capacitance direct voltage output circuit, and the output circuits are connected in series opposition between the frequency discriminator output terminals.

The low-pass lter |53, |55 and the high-pass filter |59, |6| are so adjusted that an input signal of a predetermined frequency, e. g. 100 cycles per second, is equally attenuated in the two filters, so that equal voltage amplitudes are applied to the grid circuits of the two amplifiers |5| and |51 and equal output voltages result, with the rectified output voltages cancelling to provide zero net output. An input signal of a higher frequency is attenuated less in filter |59, |6| than in filter |53, |55, and accordingly the direct voltage developed across output capacitor |62 exceeds that across output capacitor |63, with the result that a net output voltage is developed between the frequency discriminator output terminals, of a polarity corresponding to the voltage polarity across capacitor |62. An input signal of a frequency lower than the predetermined frequency, on the other hand, produces a net output voltage of the opposite polarity` In the foregoing illustrations, the present invention has-been described principally as embodied in railway vehicles. In Figs. 9 and 10 it is shown applied to steerable vehicles such as automobiles. In the automobile versions, the speed signal and auxiliary signal features of Figs. l1--6 mayv be retained along with steering control features here described.

Fig. 9 illustrates forward portions of an automobile undercarriage, including the front axle portion |61 and a longitudinal portion of the frame, the front wheels |69 and |1| on bearing members pivoted in the frame member |61 for steering deflections, and knuckle arms |13 and fixed to the wheel bearing members and in- A similar amplier stage |51 is couterconnected by a tie rod |11. Steering gear mechanism |19 is mounted on the frame at the terminus of the steering column |8| and is connected to the tie rod |11 by a connecting link |83.

A flexible recording medium such as a wire.

|84 adapted for magnetic recording is carried by a reel |85 upon the automobile, and is passed through a guide |81 and a magnetic recorder head |89 and thence over a pulley |9| arranged just at the level of the roadway paving to lay the recording medium upon the road surface during the progress of the Vehicle. The pulley |9| and recorder head |89 are carried upon a forwardly extending arm |93 pivoted at |95 about a vertical axis through the frame member |61. The arm |93 includes a rearwardly extending part slotted at |91 for engaging a pin in the tie rod |11.

As the vehicle of Fig. 9 travels along the roadway, speed signal recording equipment of the type shown in Fig. 5 operates through the recorder head |89 to impress a record upon the medium |84 for speed reference by vehicles subsequently travelling along the roadway; and the recording medium is at the same time laid along the roadway in lateral position for steering guidance of the subsequently travelling vehicles, the path of the medium-laying pulley |9| moving generally to the right or to the left with the general trends of movement of the vehicle, and being additionally deflected immediately to the right or to the left as the steering gear deflects the wheels in steering to the right or left.

Fig. 10 illustrates forward portions of an automobile under-carriage, including the front axle member |68 of the frame, the front wheels |10 and |12 on bearing members pivoted in the frame member |68 for steering deflections, and knuckle arms |14 and |16 fixed to the Wheel bearing members and connected together by a tie rod |18. Steering gear mechanism |82 is mounted on the frame at the terminus of the steering column and is connected to the tie rod |18 by a connecting link |84.

A pair of similar pickup coils 28| and `203 are arranged at opposite sides on a forwardly extending arm |94 pivoted at |96 about a Vertical axis through the frame member |68. The arm |13@4 includes a rearwardly extending part slotted at |98 for engaging a pin in the tie rod |13. The assembly of pickup coils is thus coupled to the steering assembly of the vehicle in Fig. 10 in the same manner as the coupling of the recorder head and medium-laying apparatus to the steering assembly in the vehicle of Fig. 9.

A servo system is provided on the vehicle in Fig. 10 for operating the steering system thereof in such a way as always to maintain pickup coils 20| and 203 symmetrically disposed above the prepared recording medium indicated by the curving broken line. Such a servo system may take the form of a motor 205 coupled to the steering control shaft 281 as through a gear train 2 09, and amplifier means for reversibly controlling the motor 205 according to the difference of strength of the signals developed in the left-hand coil 20| and the right-hand coil 203, the amplifier and motor connections being .sensed for deflecting the steering system and the'pickup assembly to the right when the signal strength in pickup coil 203 exceeds that in pickup coil 20|, and to the left when the signal strength in pickup coil 20| exceeds that in coil 203.

The amplifier means for controlling the motor 205 may comprise a phase-detector-amplier stage 2|| in which a pair of ampliertubes 2|3 9 and 2f|51havetheir control electrodes orfgrids-con- 'nected l'for opposite-phase excitation vas 'through a 'transformer 2|'1'| -having its primary winding -energ-ized-by'theoutput circ-uitof .a signal ampli- -fier 2-|"-9. 'The input circuit of lamplifier l2|9 is connected lLto pickup.coi-ls'2-0.| and 2.03, which are connected in series opposition. Thesefcoils gprovide cophasal lsignals at their -outer ends with 'respect to the common connection between them, and the resultant ysignal is thus -zero `when the ycoils are symmetrical about the recording -medium. When the coils 'depart fromlthe -position of symmetry, the voltage induced in the -one Anearer the medium exceeds .that v@in the lopposite AcoiLand a netidifferencefoutput voltage is there- -fore supplied between the input terminals of amplifier 219, `of amplitude dependent 4upon ythe extent of departure from symmetry and -of one phase or the opposite phase dependent upon whether the departure is to the left or right. A :further pickup coil `22| is positioned neutrally V'between coils `20| and 203 for developing a phase reference -voltage during the movement of the vehicle. This coil 22| is connected A-to the input circuit of an amplifier 223, which may be ofthe type illustrated in Fig. '7. Output Lvoltage J.from amplifier 223 is applied cophasally in the vgrid 'circuits of the tubes v2li! and 215 in lunit 2| I, as through a transformer :225 having its secondary winding connected between the secondary centertap terminal of'transformer 2|`| and a grid-'bias V'source'22'l connected to "the cathodes of tubes 253 Y and 215.

`The Aamplitude-limited output of amplier 2.23 is employed not only for reference-phase excitation of -the phase-detector-ampliner unit 42 I but also for cooperating with speed control servo apparatus 229 `which includes a frequency discriminator of the type shown in'Fig 8 and throtltle servo motor and potentiometerjelements of the 5'type shown in Fig. Vv6. f Y The anodes of tubes l2|3 'and 2|5 are vsupplied 'throught resistors 23| and 233 by an anode'power source 235. The anodes are connected to the eld supply terminals of motor 205, and the armature power vfor the motor 'is supplied by a -source 231. l

The steerable vehicles of Figs. `9 and 10 vprovide the advantages of accurate speed performance duplication as achieved in the `vehicles of Figs. '5

and `6 combined with accurate steering performance duplication. The vehicle of Fig. .9 simultaneously prepares the recording medium with 'space-alternations vfor `speed reference ol subsequent lvehicles and positions the recording .me-

dium along the path Vvfor ,guidance of the subsequent vehicles. vThe `number of cycles per unit lengthalong the :recording medium is varied not only with Variations of the speed vof the recording vehicle, :but also with variations of Athe position of the speed -control member or members of the vehicle. The lateral positioning of the recording medium-relative to the center line .of the .roadway or vehicle-path 'varies vnot only with the lateral component of movement of the recording vehicle, -but also withthe movement ofthe steeringcontrol apparatus on the vehicle. .As a result, `.the accuracy with which the subsequent vehicle l.voi

loduplicates the performance of the `recording vehicle may be .made to ,approach perfection when the speed and steeringservosystemsffoffthe vehicle .l0 are made to respond promptly to changes of frequency and to changes of rthedii- :ferential output from the side lcoils 20| Land .203.

.Sincemany changes .could 'be-made inthe-above 'construction and many 'apparently widely diierent'embodiments `of this invention couldbe made without departing from the scope thereof, it is intended that all matter contained v in 'the Vabove description or-shown in the accompanying draW- ings shall be `interpreted as illustrative and not in a limiting Isense.

What vis claim-ed is:

1. A method of preparing a recording yfor enabling the progress of a first steera'ble, variable- 'Speed Vehicle 'along `a path yto be duplicated by further vehicle, comprising operating 'said -first vehicle along `said path with steering and `speed varied according to vthe .character of successive parts of the path, and recording a chain of space-alternations and positioning said recorded chain of space-alternations along said path generally along 4'the course Ytraversed by said first vehicle, 'the number of said space alternations per unit length along 'a portion of said path being variedjointly according to the vSpeed and the motive power of said first vehicle, and the lateral .position of said .chain of space al- 'ternations .being varied jointly according .to vthe course and the steering deflection .of said first vehicle, said step of recording a chain of space alternations comprising generating an alternating signal, varying the frequency oi .saidsienal in predetermined relation to the motive power of said irst vehicle, .and recording Said signal during the movement .of said iirst vehicle.

2. A process of preparing a recording ci vthe performance of a first controllable yvehicle in vprogress along a path for enabling asecond vehicie to duplicate the performance .of said uiii-.st

vehicle, comprising operating a progress control element of .said first vehicle and thereby altering its progress for maintaining optimum p er- .formamos Yalong .successive ,portions .of said path, recording the progress .of Ysaid vehicle on a .recording medium .along said path with changes in the vehic1eprogress ,represented by corresponding changes in a predetermined characteristie of the recording, the changes in said .predetermined characteristic .beirog further modified kaccording to operation of said progress controi element, said first controllable vehicle comprising a vehicle havingaspeed-control throttle member comprising said progress control element,

said .step .of ,recording the .progress of v said vehicle in a recording medium comprising irnvpressing .significant .spacealternations .along said recording medium with .the `number o f space Aalternations per .unit length therealong normal- 1y varied .as .a predetermined function of vehicle 4speed, `and .said .further .modification o f said predetermined .characteristic 4comprising .the modiiication of the .relation between `the number of space Aalternatioiis per unit length and the vehicle speed .according to ychangeset adjustment o1" said vehicle speed ,control v throttle member. y

.3. A process of =preparing a .recording of .the performance Vof .a irst controllable Vehicle in progress along a path, for enabling a second vehicle to duplicate the perfor-mance of said first vehicle, comprising operating 1a .progress con-trol element of said frst vehicle and thereby altering its progress Itor maintaining optimum performance .along successive portions of said path, recording the progress -of .said vehicle on .a recording medium along said path with changes in the .vehicle `progress represented by corresponding .changes in a predetermined characteristie of .the recording, the .changes in said pre- 1l determined characteristic being further modified according to operation of said progress control element, said first controllable vehicle comprising a, vehicle having a steering control member comprising said progress control element, said step of recording the progress of said vehicle in a recording medium including the step of fixing the positional relation of the recording medium relative to said path according to the course of movement of said vehicle relative to said path, and said further modication of the changes in said predetermined characteristic comprising variation of the lateral position of said medium relative to said vehicle according to changes of adjustment of said steering control element.

4. A methodof preparing a signal storage along a vehicle path, comprising operating a steerable vehicle along said path, carrying a supply of recording medium on said vehicle, impressing signal variations on said medium and depositing said medium generally along the line of movement of said vehicle, and superimposing lateral deflections of said medium relative to the line of movement of said vehicle according to steering deflections of said vehicle.

5. A method of preparing a vehicle speed signalling recording medium along a vehicle path, comprising operating a speed controllable vehicle along said path, varying the vehicle speed f for optimum speeds along said path, and irn- Apressing upon said recording medium signals representing the speed of said vehicle along said path and laterally positioning said impressed recording medium along the line of travel of said n vehicle during movement of said vehicle along said path, said last step including the variable lateral deflection of said medium relative to said vehicle.

6. Apparatus for denoting the progress of a f vehicle relative to a recording medium extending along a vehicle path and characterized by space alternations therealong, comprising: pickup means carried by said vehicle and movable relative to said vehicle for travelling along said recording medium as said Vehicle traverses said path for producing alternating signals of frequency dependent upon the speed of movement of said vehicle, said pickup means including means for producing a first signal and a second signal as said Vehicle traverses said path, means coupled to said pickup means and responsive to said rst signal for varying the motive power of said vehicle according to the number of alternations per unit length along said recording medium, and means coupled to said pickup means and jointly responsive to said first signal and said second signal for varying the deflection of said pickup means to right or left from its neutral position relative to said vehicle according to relative variations of said signals and for varying the steering of said vehicle in accordance therewith, said last-defined means comprising means including a mechanical coupling between said pickup means and the steering mechanism of said vehicle for maintaining a predetermined relation between the vehicle steering and the deflection of said pickup means from the neutral position thereof.

7. Apparatus as defined in claim 6, wherein said means coupled to said pickup means for varying the position of said pickup means comprises phase-responsive means for varying the position of said pickup means according to the relative phase of said first and second signals.

8. Apparatus for preparing a vehicle signalling recording medium according to the speed and course of movement of a steerable vehicle, comprising means for recording an alternating signal in successive parts of said medium during movement of said vehicle and positioning said recording medium generally along the course of movement of said vehicle, means for simultaneously defiecting said recording medium relative to said line of movement and deecting the steering of said vehicle in coordinated relation, and means for simultaneously varying the motive power of said vehicle and the frequency of the signal recorded.

9. Apparatus for preparing Aa vehicle signalling recording medium according to the speed of movement and the motive power exerted on a vehicle, comprising recording means carried by said vehicle, said recording means being arranger. for relative movement with respect to said medium at a speed varying according to the speed of movement of said vehicle, means for applying vto said recording means an alternating signal of substantially constant frequency during operation of said vehicle at substantially constant speed and power, and means for Varying the frequency of said signal as a predetermined function of variations of motive power of said vehicle, said recording means including means for impressing upon said medium a lasting record of said signal.

10. A method of causing a second steerable vehicle with a steering control to travel along a path with progress variations substantially duplicating those of a first or pilot steerable vehicle with a steering control, comprising operating the first vehicle along the path, laying a continuous-strip recording medium generally along the path with lateral displacement relative to the first vehicle according to the steering control displacement of the first vehicle as it progresses along the path, operating the second vehicle along the path, and deflecting the steering control of said second vehicle according to relative lateral displacement between said second vehicle and said medium.

11. The method of causing a second steerable vehicle to travel along a path with progress variations substantially duplicating those of a first or pilot steerable vehicle as dened in claim l0, further including the steps of impressing upon said recording medium adjacent the first vehicle as it progresses therealong regular variations signifying the variations of speed of said first vehicle, detecting said impressed variations as said second vehicle traverses them in its progress, and varying the speed of said second vehicle according to thedetected variations.

THOMAS M. FERR-ILL, JR

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